Median effective concentration of sevoflurane inhibiting responses to laryngel mask airway removal in pediatric patients under comprehensive clinical conditions

Objective To determine the median effective concentration(EC50)of sevoflurane inhibiting responses to laryngeal mask airway(LMA)removal in pediatric patients under comprehensive clinical conditions. Methods Twenty-six pediatric patients of both sexes, aged 1-5 yr, with body mass index of 15-20 kg/m2, of American Society of Anesthesiologists physical statusⅠ, scheduled for elective minor surgery, were enrolled in this study.Anesthesia was induced by inhaling 8% sevoflurane and injecting dezocine 0.1 mg/kg.The LMA painted with Teracainum Plasmagel was inserted.Anesthesia was maintained by sevoflurane inhalation and target-controlled infusion of remifentanil.Remifentanil infusion was stopped at 5 min before the end of surgery.At the end of surgery, the end-tidal concentration of sevoflurane was maintained at the target concentration for at least 10 min and then the laryngeal mask airway was removed.The end-tidal concentration of sevoflurane was determined by using Dixon′s up-and-down sequential method.The end-tidal concentration of sevoflurane was set at 0.8% in the first pediatric patient.Each time the concentration of sevoflurane increased/decreased by 0.1% in the next pediatric patient according to patient′s responses to LMA removal. Results The EC50 of sevoflurane inhibiting responses to LMA removal was 0.59%, and the 95% confidence interval was 0.55%-0.63% in pediatric patients under comprehensive clinical conditions. Conclusion The EC50 of sevoflurane inhibiting responses to LMA removal is 0.59% in pediatric patients under comprehensive clinical conditions. Key words: Anesthetics, inhalation; Laryngeal masks; Dose-response relationship, drug; Child